Telecommunications chassis and card

ABSTRACT

A chassis and associated telecommunication circuit card are disclosed. The chassis has heat dissipation structures and may accommodate a high density of the circuitry cards. Embodiments may include one surface with one or more ridges for rigidity and ventilation and fin slots for receiving circuit card guide fins. Embodiments may include a surface with knockouts for receiving circuit card guides. Embodiments may also include multiple bracket hole patterns for mounting brackets for different racks or for a single multi-rack bracket having more than one mounting hole pattern. The circuit card includes conductor structures such as multiple board layers with paired and segregated conductors. The circuit card also includes some components positioned to cooperate with the ventilation structures of the chassis and includes some components chosen for low-power consumption or reduced flammability.

TECHNICAL FIELD

This invention relates to chassis for holding telecommunications cardssuch as repeater circuits. More specifically, the present inventionrelates to chassis and cards with structures for high card density andstructures for mounting with multiple rack styles.

BACKGROUND

It is desirable for a chassis for holding telecommunication circuitcards to support a high density of cards, yet the chassis musteffectively dissipate heat developed during operation. The cardsinstalled in the chassis perform electrical operations, such as signaltransception and amplification that generate a significant amount ofheat. Typically, a chassis is installed in a particular rack thatcontains several other chassis stacked above and below. The heat thatmay develop within a chassis in the rack has the potential to harmcircuit cards housed in the chassis above and below the chassis wherethe heat emanates from. Additionally, the rack housing the chassis maybe one of several different rack types, such as an EIA rack style, aWECO rack style, or an ETSI rack style, and a different chassis may berequired for each to ensure proper mounting.

The chassis must also provide external protection for the circuit cardsit houses. Thus, the chassis cannot freely expose the circuit cards toareas outside the chassis when attempting to dissipate heat.Additionally, the chassis must provide a structural interconnection thatmaintains electrical continuity between the circuit cards and externaltransmission mediums such as copper wires or fiber optic cables whilefacilitating insertion and removal of the cards. A sufficient structuremust be used to facilitate this circuit card modularity, which furtherlimits the chassis' ability to provide outlets for heat.

Additionally, to reduce the chassis size for a given number of circuits,the circuit card density must be increased. Increasing circuit carddensity is difficult not only due to heat dissipation, but also becauseof electromagnetic noise that must be contained. Generally, increasingcircuit card density involves employing smaller cards, and smaller cardsrequire higher component density within the cards.

Achieving effective heat dissipation with adequate electromagnetic noisecontainment may even be more difficult for smaller card designs withhigher component densities.

Thus several factors must be accounted for in the chassis and carddesign. Chassis designs with large interior spaces for directing heataway from circuit cards may be undesirable because the chassis maybecome too large when accommodating a high density of circuits. Chassisdesigns with open exteriors for directing heat away from the circuitcards may be undesirable because the circuit cards may not besufficiently protected from externalities such as falling objects orheat spreading from a chassis positioned above or below in the rack.Card designs that are relatively large require a larger chassis to housethe same quantity of cards. Additionally, a different chassis must beprovided for each rack style for proper mounting.

Thus, there is a need for a chassis and card design whereby the chassismay contain a high density of readily removable circuit cards whileproviding effective heat dissipation and electromagnetic noisecontainment and/or be mountable in multiple rack styles.

SUMMARY

The present invention provides a chassis and card design that mayaccommodate a high density of readily removable circuits while providingheat dissipation and electromagnetic noise containment features.Ventilation structures are employed to direct heat away from internalcircuitry. Additionally, chassis designs of the present invention mayprovide exterior features that establish protection from externalitiesand prevent the harmful spread of heat to chassis or other equipmentstacked above or below. Card designs of the present invention mayprovide conductor structures for containing electromagnetic noise and/orindividual components placed in locations for coordination with theventilation structures of the chassis. Additionally, the chassis mayprovide configurable mounting structures to enable a single chassis tobe mounted in racks of different styles.

The present invention may be viewed as a chassis for housingtelecommunications cards. The chassis includes a housing having a firstand second horizontal surface and vertical sidewalls between the firstand second horizontal surfaces. The first and second horizontal surfaceshave a plurality of openings, and the first horizontal surface has afirst ridge substantially perpendicular to a longitudinal axis of thevertical sidewalls. The chassis also includes a first horizontal coveroverlaying the first horizontal surface, and the first horizontal coverhas a first ridge that is aligned with the first ridge of the firsthorizontal surface.

The present invention may also be viewed as another chassis for holdingtelecommunications cards. The chassis includes a housing having a firstand second horizontal surface and vertical sidewalls between the firstand second horizontal surfaces. The first and second horizontal surfaceshave a plurality of openings, wherein the second horizontal surface hasa first ridge substantially perpendicular to a longitudinal axis of thevertical sidewalls, and the first ridge has a plurality of knockouts.Each knockout is for receiving a guide of a telecommunications card.

The present invention may also be viewed as a chassis for housingrepeater cards. The chassis includes a housing with vertical sidewalls,a first horizontal surface, and a second horizontal surface, wherein thefirst horizontal surface has a first ridge extending substantiallyperpendicular to a longitudinal axis of the vertical sidewalls and asecond ridge substantially parallel to the first ridge. The first ridgeand the second ridge each have an elongated opening. The chassis alsoincludes one or more repeater cards positioned between the firsthorizontal surface and the second horizontal surface, and the one ormore repeater cards have a DC-DC converter and a transceiver. The DC-DCconverter is positioned at least partially between the elongated openingof the first ridge and the second surface. The transceiver is positionedat least partially between the elongated opening of the second ridge andthe second surface.

The present invention may be viewed as another chassis for holdingtelecommunications cards. The chassis includes a housing having firstand second horizontal surfaces and first and second vertical sidewalls,and the first vertical sidewall having a plurality of holes. The chassisalso includes a first bracket mounted to the housing, with the firstbracket having a first side and a second side perpendicular to the firstside. The first side of the first bracket has a first horizontaldimension and a first and second set of holes, and the second side ofthe first bracket has a second horizontal dimension different than thefirst horizontal dimension and has a first and second set of holes. Whenthe first set of holes of the first side of the first bracket align withat least a portion of the plurality of holes of the first sidewall, thesecond set of holes of the first side of the first bracket are blockedby the first vertical sidewall. When the first set of holes of thesecond side of the first bracket align with at least a portion of theplurality of holes of the first vertical sidewall, the second set ofholes of the second side of the first bracket are blocked by the firstvertical sidewall.

The present invention may be viewed as another chassis for holdingtelecommunications cards. The chassis includes first and secondhorizontal surfaces and first and second vertical sidewalls separatingthe first and second horizontal surfaces, wherein the first verticalsidewall has a plurality of at least three holes. The chassis alsoincludes a first bracket having a first side and having a second sidesubstantially perpendicular to the first side, the first side having aset of at least two holes and the second side having a set of at leasttwo holes. The set of at least two holes of the first side align with afirst set of at least two but fewer than all of the plurality of holesof the first vertical sidewall when the first side abuts the firstvertical sidewall. The set of at least two holes of the second sidealign with a second set of at least two but fewer than all of theplurality of holes of the first vertical sidewall when the second sideabuts the first vertical sidewall. The first set includes at least onehole not included in the second set.

The present invention may be viewed as a method of installing bracketson a chassis. The method involves providing a housing having first andsecond horizontal surfaces and first and second vertical sidewalls, withthe first vertical sidewall having a plurality of holes. The method alsoinvolves providing a first bracket having a first side and a second sideperpendicular to the first side, wherein the first side of the firstbracket has a first horizontal dimension and a first and second set ofholes and wherein the second side of the first bracket has a secondhorizontal dimension different than the first horizontal dimension andhas a first and second set of holes. When installing the first bracketsuch that the first side abuts the first vertical sidewall, the methodinvolves aligning the first set of holes of the first side of the firstbracket with at least a portion of the plurality of holes of the firstsidewall and blocking the second set of holes of the first side of thefirst bracket by the first vertical sidewall. When installing the firstbracket such that the second side abuts the first vertical sidewall, themethod involves aligning the first set of holes of the second side ofthe first bracket with at least a portion of the plurality of holes ofthe first vertical sidewall and blocking the second set of holes of thesecond side of the first bracket by the first vertical sidewall.

The present invention may be viewed as another method of installingbrackets on a chassis. The method involves providing a housing havingfirst and second horizontal surfaces and first and second verticalsidewalls separating the first and second horizontal surfaces, whereinthe first vertical sidewall has a plurality of at least three holes. Themethod further involves providing a first bracket having a first sideand having a second side substantially perpendicular to the first side,with the first side having a set of at least two holes and the secondside having a set of at least two holes. When installing the bracketsuch that the first side abuts the first vertical sidewall, the methodinvolves aligning the set of at least two holes of the first side with afirst set of at least two but fewer than all of the plurality of holesof the first vertical sidewall. When installing the bracket such thatthe second side abuts the first vertical sidewall, the method involvesaligning the set of at least two holes of the second side with a secondset of at least two but fewer than all of the plurality of holes of thefirst vertical sidewall, wherein the first set comprises at least onehole not included in the second set.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top front perspective view of an empty chassis in accordancewith one embodiment of the present invention.

FIG. 2 is a top rear perspective view of the empty chassis.

FIG. 3 is a bottom front perspective view of the empty chassis.

FIG. 4 is a bottom rear perspective view of the empty chassis.

FIG. 5 is a top view of the empty chassis.

FIG. 6 is a front view of the empty chassis.

FIG. 7 is a right side view of the empty chassis.

FIG. 8 is a bottom view of a loaded chassis.

FIG. 9 is a rear view of the loaded chassis.

FIG. 10 is a left side view of the loaded chassis.

FIG. 11 is a partially exploded top rear perspective view of the emptychassis.

FIG. 12 is a partially exploded top rear perspective view of the emptychassis with a top and a bottom mesh cover removed.

FIG. 13 is a top view of the loaded chassis with the top mesh coverremoved.

FIG. 14 is a front view of the loaded chassis.

FIG. 15 is a right side view of the loaded chassis.

FIG. 16 is a top front exploded perspective view of the empty chassis.

FIG. 17 is a top rear exploded perspective view of the empty chassis.

FIG. 18 is a right side view of the empty chassis with the right sidepanel removed.

FIG. 19 is a bottom view of the empty chassis with the bottom mesh coverremoved.

FIG. 20 is a top view of the empty chassis with the top mesh coverremoved.

FIG. 21 is a top front perspective view of the chassis with cards beinginserted.

FIG. 22 is a top front perspective view of the chassis with three spacedcards being inserted in knock-outs and fin slots within horizontalsurfaces of the chassis.

FIG. 23 is an exploded perspective view of the backplane.

FIG. 24 is a top view of the backplane.

FIG. 25 is a rear view of the backplane.

FIG. 26 is a left side view of the backplane.

FIG. 27 is a top view of the circuit card.

FIG. 28 is a right side view of the circuit card.

FIG. 29 is a bottom view of the circuit card.

FIG. 30 is a front view of the circuit card.

FIG. 31 is a rear view of the circuit card.

FIG. 32 is an exploded top rear perspective view of the circuit card.

FIG. 33 is an exploded top front perspective view of the circuit card.

FIG. 34 is a perspective view of the card mounted in relation to a topsurface of the chassis.

FIG. 35 is a perspective view of the card mounted in relation to abottom surface of the chassis.

FIGS. 36A and 36B are a right side view of components mounted inrelation to a circuit board of the circuit card.

FIGS. 37A-37E are a schematic of alarm circuitry of the circuit board.

FIGS. 38A-38G are a schematic of transceiver configuration circuitry ofthe circuit board.

FIGS. 39A and 39B are a schematic of power supply circuitry of thecircuit board.

FIG. 40 is a view of a ground layer of the circuit board.

FIG. 41 is a view of a power layer of the circuit board.

FIGS. 42A and 42B are a view of a component layer of the circuit board.

FIG. 43 is a perspective view of the empty chassis mounted in an EIArack using a first mounting method.

FIG. 44 is a front view of the empty chassis mounted in the EIA rackusing the first mounting method.

FIG. 45 is a perspective view of the empty chassis mounted in the EIArack using a second mounting method.

FIG. 46 is a front view of the empty chassis mounted in the EIA rackusing the second mounting method.

FIG. 47 is a perspective view of the empty chassis mounted in a WECOrack.

FIG. 48 is a front view of the empty chassis mounted in the WECO rack.

FIG. 49 is a perspective view of the empty chassis mounted in an ETSIrack.

FIG. 50 is a front view of the empty chassis mounted in the ETSI rack.

FIGS. 51A and 51B are a side view of an alternative circuit board of thecircuit card having input amplification and additional surge protectioncomponents.

FIGS. 52A and 52B are a schematic of transceiver configuration circuitryof the repeater circuit employing additional surge protectioncomponents.

FIGS. 53A and 53B are a schematic of power supply circuitry of therepeater circuit employing additional surge protection components.

FIG. 54 is a view of an alternative ground conductor layer of theprinted circuit board that employs the additional surge protectioncomponents.

FIG. 55 is a view of an alternative power conductor layer of the printedcircuit board that employs the additional surge protection components.

DETAILED DESCRIPTION

Various embodiments of the present invention will be described in detailwith reference to the drawings, wherein like reference numeralsrepresent like parts and assemblies through the several views. Referenceto various embodiments does not limit the scope of the invention, whichis limited only by the scope of the claims attached hereto.

FIGS. 1-7 show an embodiment of the chassis 100 for holdingtelecommunications cards. The empty chassis 100 of FIGS. 1-7 has ahorizontal surface 102 mounted to vertical sidewalls 120, 122. In thisembodiment, each vertical sidewall 120, 122 has a 90 degree bend at thefront and rear ends allowing the sidewalls 120, 122 to form partialfront and rear panels of the chassis 100. The vertical sidewalls 120,122 have a longitudinal axis that extends from the front to the back ofthe chassis 100, which is from the front bend to the rear bend in theembodiment shown. The chassis 100 also has a horizontal surface 142mounted to the vertical sidewalls 120, 122. Both horizontal surfaces102, 142 and both sidewalls 120, 122 of this embodiment are made of amaterial such as cold-rolled steel. The cold-rolled steel may have achromate plating to reduce electromagnetic interference.

Covers are provided over the first horizontal surface 102 and the secondhorizontal surface 142. The first horizontal cover 104 overlays thefirst horizontal surface 102 and mounts directly to it. The secondhorizontal cover 154 underlays the second horizontal surface 142 andmounts directly to it. The covers 104 and 154 of this embodiment aremade of a mesh surface such as aluminum having 63% of its area formed bydensely populated openings. Other materials and air passage percentagesare also applicable. The mesh material allows rising air to pass throughwhile preventing objects from falling into or out of the chassis 100that would otherwise enter the chassis 100 through large openingsprovided in the first and second horizontal surfaces 102, 142 that arediscussed below.

The first horizontal surface 102 is contoured to provide two ridges 300,304 dividing three recessed areas 103, 302, and 306, as is best seen inFIG. 12. The two parallel ridges 300, 304 extend across the width of thechassis 100 perpendicularly to the longitudinal axis of the verticalsidewalls 120, 122. The first area 103 of the first horizontal surfaceextends beyond the coverage area of the first horizontal cover 104. Thefirst horizontal cover 104 of this embodiment is also contoured toprovide two ridges 105, 108 and two recessed areas 106 and 110. Theridge 105 of the first horizontal cover 104 is aligned with and overlapsridge 300 of the first horizontal surface 102. The ridge 108 of thefirst horizontal cover 104 is aligned with and overlaps ridge 304 of thefirst horizontal surface 102. The recessed area 106 of the firsthorizontal cover 104 overlaps with recessed area 302 of the firsthorizontal surface 102, and the recessed area 110 of the firsthorizontal cover 104 overlaps with recessed area 306 of the firsthorizontal surface 102.

The first horizontal surface 102 includes a first row of fin slots 118in area 103 that are for receiving a fin of a circuit card, discussedbelow. The first row of fin slots 118 extends into the ridge 300 and thefin slots are perpendicular to the longitudinal direction of the ridge300. The first horizontal surface 102 also includes a second row of finslots 196 that extend across the area 302 from the ridge 300 to theridge 304. The first horizontal surface 102 also includes a third row offin slots 202 in area 306 that extends into the ridge 304. The fin slotsof each row align with fin slots in the other rows and guide eachcircuit card as it is inserted into the chassis 100. The ridges 300, 304add rigidity to the first horizontal surface by allowing the fin slotsto be broken into sets of rows while allowing the fin of the card topass by as it is being inserted. The rigidity of the first horizontalsurface 102 would be reduced if the ridges 300, 304 were not presentbecause each fin slot would need to be continuous to facilitate circuitcard entry rather than being broken into three sections as shown.

The first horizontal cover 104 has a row of fin slots 116 in the area106 that align with the row of fin slots 196 in the area 302 of thefirst horizontal surface 102. The first horizontal cover 104 also has arow of fin slots 114 in the area 110 that align with the row of finslots 202 in the area 306 of the first horizontal surface 102. The rowsof fin slots in the first horizontal cover 104 also allow the fin of thecircuit card to be guided as it is inserted into the chassis 100.Similar to the first horizontal surface 102, the rigidity of the firsthorizontal cover 142 would be reduced if the ridges 105, 108 were notpresent because each fin slot would need to be continuous to facilitatecircuit card entry rather than being broken into two sections as shown.

In the embodiment shown, the chassis 100 has open interior regions oneach side defined by the wrap-around vertical sidewalls 120, 122. Thefirst horizontal surface 102 has ventilation holes 112 over the leftregion in the area 103 and ventilation holes 150 over the right regionin the area 103. Also in the area 103, the first horizontal surface hasventilation holes 152 placed between each fin slot of the first row 118.The second horizontal surface has ventilation holes 148 under the leftregion and ventilation holes 146 under the right region.

Because the chassis is empty in FIGS. 1-7, card slot covers 132 aremounted to the chassis 100 to avoid exposing the interior of the chassis100. The rear of the chassis 100 is enclosed by a backplane 128 that isattached to each wrap-around vertical sidewall 120, 122. The backplane128 provides connections between cables and the circuit cards housed bythe chassis 100. The backplane 128 includes external connectors 130 thatconnect to cables routed to the rear of the chassis rack (not shown)where the chassis 100 is installed.

The rear of the chassis 100 includes a cover 134 made from a materialsuch as lexan that may be placed over a portion of the backplane 128where circuit leads and pins from card connectors, discussed below, arepresent. A cable bar 136 may also be installed to hold the cablesconnected to the external connectors 130. A chassis ground connector 138may also be included for grounding the chassis 100.

The second horizontal surface 142 may include a first ridge 183 spanningthe width of the chassis 100 and being parallel to the ridge 300 of thefirst horizontal surface 102. The first ridge 183 may include a row ofknockouts 144 for receiving a guide of a circuit card. The knockout 144is a portion of the ridge 183 that has been removed to create a passagefor the guide. As shown, the card slot covers 132 have a guide 131 thatfits into the knockout 144 to stabilize the bottom of the card slotcover 132. As shown in FIG. 12, the second horizontal surface 142 mayalso include a second ridge 185 positioned near the backplane 128 andextending substantially parallel to the ridge 183 across the width ofthe chassis 100. An area 182 is provided between the second ridge 185and the backplane 128. The second ridge 185 also includes knockouts 147for receiving the guide of the circuit cards.

The chassis 100 of this embodiment also includes mounting brackets 124,126. These brackets 124, 126 mount to the vertical sidewalls 120,122 andalso to the vertical rails of a chassis rack (not shown). The brackets124, 126 of this embodiment facilitate mounting the chassis 100 indifferent racks. The bracket 124, 126 has a first side 123, 129 thatabuts the vertical sidewall 120, 122, such as in FIGS. 1 and 2, andanother side 125, 127 that is perpendicular to the first side 123, 129and that abuts the rack rail when mounting the chassis 100.

The first side 123, 129 has a first horizontal dimension and the secondside 125, 127 has a second horizontal dimension different than the firsthorizontal dimension. The differing horizontal dimensions of the sidesof the bracket 124, 126 allow the bracket 124, 126 and chassis 100 to beused for racks with different mounting widths. For one rack mountingwidth, the first side 123, 129 abuts the chassis 100 and the other side125, 127 abuts the rail of the rack. For another rack mounting widththat is less wide, the second side 125, 127 abuts the chassis 100 andthe first side 123, 129 abuts the rack rail.

As best seen in FIG. 11, the side 129 of the bracket 126 has a brackethole pattern established by bracket holes 164, 166, and 168. Side 123 ofbracket 124 has the same bracket hole pattern. The sidewalls 120, 122 ofthe chassis 100 have a bracket hole pattern that matches the brackethole pattern of the sides 123 and 129. As seen in FIG. 12, this brackethole pattern of the chassis 100 includes bracket holes 165, 167, and169. The bracket holes of the chassis 100 align with the bracket holesof the bracket 124, 126 when mounting the brackets 124, 126.

When using the side 125, 127 to mount to the rack rail, a rack holeconfiguration on the side 125, 127 is available. This rack holeconfiguration includes the rack holes 176, 178, and 180. This setup isapplicable for racks such as an ETSI rack where the distance betweenadjacent rack holes 176, 178, and 180 is 25 millimeters. The ETSI rackand mounted chassis can be seen in FIGS. 49 and 50.

The ETSI rack of FIGS. 49 and 50 includes rails 342 and 344. The rails342, 344 have mounting holes with consistent spacing. The rails 342 and344 and associated mounting holes of the ETSI rack are spaced furtherapart horizontally than those of the EIA or WECO racks. Therefore, thechassis 100 includes brackets 124 and 126 mounted such that the widesides 125 and 127 extend from the chassis 100 while the narrow sides 123and 129 abut the vertical sidewalls 120, 122 of the chassis 100.

The rack holes 176, 178, and 180 of the brackets 124, 126 align withthree contiguous mounting holes 346, 348, and 350 of the rails 342, 344.The chassis 100 is fastened to the rails 342, 344 through screws thatengage the rack holes 176, 178, and 180 and the mounting holes 346, 348,and 350. Multiple chassis 100 may be stacked one directly atop the nextwithin the ETSI rack.

With reference to FIG. 11, the side 125 of the bracket 124 has a brackethole pattern established by bracket holes 158, 160, and 162. Side 127has the same bracket hole pattern. The sidewalls 120, 122 of the chassis100 have a bracket hole pattern that matches the bracket hole pattern ofsides 125 and 127. As seen in FIGS. 11 and 12, this bracket hole patternof the chassis 100 includes brackets holes 159, 161, and 163.

When using the side 123, 129 to mount to the rack rail, a rack holeconfiguration on the side 123, 129 is available. This rack holeconfiguration includes the rack holes 170, 171, 172, and 174. This setupis applicable for racks such as an EIA or WECO rack where the distancebetween adjacent rack holes 170, 171, and 172 is 0.5 inches and thedistance between the adjacent rack holes 172 and 174 is 1.25 inches. TheEIA rack and mounted chassis can be seen in FIGS. 43 and 44 for a firstmounting method and FIGS. 45 and 46 for a second mounting method. TheWECO rack and mounted chassis can be seen in FIGS. 47 and 48.

The EIA rack of FIGS. 43, 44, 45, and 46 includes rails 322 and 324. Therails 322, 324 have paired mounting holes with one spacing distancebetween each hole of the pair and a greater second distance betweenadjacent holes of different pairs. Because the rails 322 and 324 andassociated mounting holes of the EIA rack are spaced more closelyhorizontally than those of the ETSI rack, the chassis 100 includesbrackets 124 and 126 mounted such that the narrow sides 123 and 129extend from the chassis 100 while the narrow sides 125 and 127 abut thevertical sidewalls 120, 122 of the chassis 100.

For the first method of mounting shown in FIGS. 43 and 44, the rackholes 171, 172, and 174 of the brackets 124, 126 align with threecontiguous mounting holes 326, 328, and 330 of the rails 322, 324. Themounting holes 326 and 328 are of one pair, and mounting hole 330 ispaired with mounting hole 332. Both the mounting hole 332 of the rails322, 324 and the rack hole 170 of the brackets 124, 126 are unused inthis method. The chassis 100 is fastened to the rails 322, 324 throughscrews that engage the rack holes 171, 172, and 174 and the mountingholes 326, 328, and 330. Multiple chassis 100 may be stacked one atopthe next in the EIA rack using this first mounting method and a smallgap will be provided between each chassis 100.

For the second method of mounting shown in FIGS. 45 and 46, the rackholes 171, 172, and 174 of the brackets 124, 126 align with threemounting holes 326, 328, and 332 of the rails 322, 324. Mounting hole330 of the rails 322, 324 and rack hole 172 of brackets 124, 126 areunused in this method. The chassis 100 is fastened to the rails 322, 324through screws that engage the rack holes 171, 172, and 174 and themounting holes 326, 328, and 332. Multiple chassis 100 may be stackedone atop the next in the EIA rack using the second mounting method aswell and a small gap will be provided between each chassis 100.

The WECO rack of FIGS. 47 and 48 includes rails 334 and 336. The rails334, 336 have mounting holes with consistent spacing distance betweeneach adjacent mounting hole. Because the rails 334 and 336 andassociated mounting holes of the WECO rack are spaced horizontally thesame distance as those of the EIA rack and are more closely spacedhorizontally than those of the ETSI rack, the chassis 100 includesbrackets 124 and 126 mounted such that the narrow sides 123 and 129extend from the chassis 100 while the narrow sides 125 and 127 abut thevertical sidewalls 120, 122 of the chassis 100.

The rack holes 170 and 172 of the brackets 124, 126 align with twocontiguous mounting holes 338 and 340 of the rails 334, 336. The rackholes 171 and 174 of the brackets 124, 126 are unused with the WECOrack. The chassis 100 is fastened to the rails 334, 336 through screwsthat engage the rack holes 17 and 172 and the mounting holes 338 and340. Multiple chassis 100 may be stacked one directly atop the next inthe WECO rack.

FIGS. 8-10 and 13-15 show the chassis 100 loaded with circuit cards 208.Each circuit card 208 has a handle 156 that extends from a faceplate 210of the circuit card 208 that the user may grip to insert or remove acircuit card 208 from the chassis 100. The faceplate 210 of each of thecards fills the card slot openings that are otherwise occupied by cardslot covers 132.

In FIG. 13, the first horizontal cover 104 is removed to show the firsthorizontal surface 102 as is also shown in FIG. 12. The first horizontalsurface 102 includes the recessed area 103 adjacent to the first ridge300. The first ridge 300 includes a row of elongated openings 194. Thefirst ridge 300 is also adjacent to the recessed area 302. The recessedarea 302 includes the second row of fin slots 196. Between each adjacentpair of fin slots 196 lies openings from a first row 192, a second row190, and a third row 186. Over the left and right empty regions lieadditional large ventilation holes 198 and 188, respectively.

Adjacent to the recessed area 302 is the second ridge 304 of the firsthorizontal surface 102. The second ridge 304 includes a row of elongatedopenings 195. Adjacent to the second ridge 304 is the recessed area 306that includes a row of fin slots 202. Between each adjacent pair of finslots 202 lie openings from a row of openings 200. Over the left andright empty regions lie additional ventilation holes 204 and 206,respectively.

FIGS. 16 and 17 shows exploded views of the chassis 100 without thefirst horizontal cover 104 and the second horizontal cover 154. Fromthese exploded views, the wrap-around structure of the verticalsidewalls 120 and 122 can be seen. Additionally, the placement of theridges 300, 304 in the first horizontal surface 102 in relation to theplacement of the ridges 183, 185 in the second horizontal surface 142 isvisible as is the pattern of openings in both surfaces.

FIG. 18 shows a right side view of the empty chassis 100 with the rightvertical sidewall 122 removed. The left vertical sidewall 120 can beseen as no cards are positioned in the chassis 100 to obstruct the viewof the sidewall 120. This side view illustrates the mounted relationshipof the card connector 224 and the external connector 130 of thebackplane 128. Also illustrated by FIG. 18 is the alignment andoverlapping position of the ridges 105 and 108 of the first horizontalcover 104 in relation to the ridges 300 and 304, respectively, of thefirst horizontal surface 102. The ridges 183 and 185 of the secondhorizontal surface 142 can be seen as can the second horizontal cover154 which does not include a ridge aligned with the ridge 185 in thisembodiment.

FIG. 19 shows an exterior view onto the second horizontal surface 142 ofthe chassis 100 with the mesh cover 154 removed. The second horizontalsurface 142 includes the first row of knockouts 144 at the front of thechassis 100. On each side of the knockouts 144 are ventilation holes 308and 310 over the empty side areas of the chassis. As shown, the bracket124 is mounted with its narrow side extending outwardly from the chassis100 while the bracket 126 is mounted with its wide side extendingoutwardly.

The second horizontal surface 142 includes the second row of knockouts147 positioned near the rear of the chassis 100. Four rows of openingsare positioned between the first row of knockouts 144 and the second rowof knockouts 147 including a first row 312, a second row 314, a thirdrow 316, and a fourth row 320. In the embodiment shown, the holes of arow alternate between long and short from one column to the nextadjacent column. Between the rear of the chassis 100 and the second rowof knockouts 147 are several smaller openings 318 that provideadditional ventilation.

Because FIG. 19 shows an empty chassis 100, the positioning of theventilation structures of the first horizontal surface 102 relative toventilation structures of the second horizontal surface 142 can be seen.The elongated opening 194 of the ridge 300 of the first horizontalsurface 102 can be seen through the first row 312 and second row 314 ofopenings in the second horizontal surface 142. Likewise, the elongatedopening 195 of the ridge 304 can be seen through the second row ofknockouts 147. The first row 186, second row 190, and third row 192 ofopenings of the first horizontal surface that lie between ridges 300 and304 can be seen through the openings 316 and 320 indicating a partialvertical alignment of openings between the first horizontal surface 102and the second horizontal surface 142. The third row of fin slots 202 ofthe first horizontal surface 102 and the rear row of openings 200 can bealso been seen through the second row of knockouts 147.

To further illustrate the relation of the ventilation structures of thesecond horizontal surface 142 in relation to those of the firsthorizontal surface 102, FIG. 20 shows an empty chassis 100 viewed ontothe first horizontal surface 102 with the first horizontal cover 104removed. The second row of knockouts 147 can be seen through the rearrow of openings 200. The knockouts 147 can also be seen through theelongated opening 195 of the ridge 304. The third row 316 and fourth row320 of openings of the second horizontal surface 142 can be seen throughthe first row 186, second row 190, and third row 192 of openings of thefirst horizontal surface 102. The first row 312 and second row 314 ofopenings of the second horizontal surface 142 can be seen through theelongated opening 194 of the ridge 300. The first row of knockouts 144can be seen through the first row of fin slots 118.

Air rises through the bottom of the chassis 100 and passes by thecircuit cards 208 installed between the first horizontal surface 102 andthe second horizontal surface 142 as the components of the circuit cards208 warm the air. In the embodiment shown, because the openings of eachhorizontal surface are not directly aligned, the warmed air is not ableto rise directly from bottom to top within the chassis 100 but may bechanneled forward, backward, and/or side-to-side before passing throughthe nearest hole in the first horizontal surface 102.

FIG. 21 shows the chassis 100 filled with circuit cards 208 and havingthree cards partially inserted. The circuit cards include a fin 212 onone edge that is received by the fin slots of the first horizontalsurface 102 and the first horizontal cover 104. The circuit card 208also has a guide 214 on an opposite edge that fits within the knockout144 of the ridge 183 of the second horizontal surface 142.

FIG. 22 more clearly shows the cooperation between the fin slots 118 ofthe first horizontal surface 102 and the fin 212 of the circuit card208. The cooperation between the guide 214 and the knockout 144 of thefirst ridge 183 of the second horizontal surface 142 is also shown. Thecard 208 is positioned with the fin 212 in the slot 118 and the guide214 in the knockout, and the card 208 is inserted until the faceplate210 abuts the front edge 216 of the first horizontal surface 102. Atthat point, a connector 225 of the card 208 engages a card connector 224of the backplane 128 discussed below. Also, in this embodiment holes218, 220, and 222 of the guide 214 have at least partially aligned withholes 312, 314, and 316 in the second horizontal surface 142 once thecard 208 is fully inserted. This alignment is more clearly shown in FIG.35.

FIGS. 23-26 are several views of the backplane 128. The backplane 128 isa printed circuit board and it has external connectors 130 mounted toone side and card connectors 224 mounted to the other side. A powersupply connector 226 is also mounted to the side with the externalconnectors 130. The connector 225 of the circuit card 208 mates to thecard connector 224 once the card 208 is fully inserted in the chassis100, and the card connector 224 establishes electrical communicationbetween the card 208 and the external connector 130. As shown in FIG. 2,the backplane 128 of the chassis 100 is vertical relative to thehorizontal surfaces 102, 142, and the vertical backplane 128 ispositioned between and perpendicular to the two vertical sidewalls 120,122.

FIGS. 27-33 are several views of the circuit card 208. The circuit card208 includes the fin 212, guide 214, faceplate 210, finger 156, andconnector 225 previously discussed. The circuit card 208 also includes aprinted circuit board 234 that has circuitry 236 mounted to it. Thecircuitry 236 may be repeater circuitry as discussed below. Lightemitting diodes (LEDs), such as power LED 228, channel A LED 230, andchannel B LED 232, may protruded from the faceplate 210. The LEDs 228,230, and 232 may illuminate as one or more colors as controlled bycircuitry 236 to indicate the state of operation of the circuitry 236.

FIG. 34 shows the card 208 mounted in the chassis 100 in relation to thefirst horizontal surface 102 and its ventilation structures. The fin 212of the card 208 is positioned within the first row 118, second row 196,and third row 202 of fin slots. The card 208 is fully inserted once thefaceplate 210 has contacted the front edge 216. The card 208 includesseveral components such as a capacitor 236, a DC-DC converter 238, atransceiver 248, relay 244, and programmable logic device 246 that arepositioned, in this embodiment, relative to the structures of the firsthorizontal surface 102. These components are discussed in more detailbelow.

The capacitor 236 lies beneath the area 103 that restricts upwardventilation and causes air to be channel toward rearward areas of thechassis 100. The DC-DC converter 238 lies partially beneath theelongated opening 194 of ridge 300. The elongated opening 194 increasesthe ventilation over the DC-DC converter 238 which generates asignificant amount of heat. The DC-DC converter 238 also partially liesbeneath the row of openings 192. The relay 244 and programmable logicdevice 246 lie beneath the row 190 and row 186 of openings. Thetransceiver 248 lies partially beneath the elongated opening 195 of thesecond ridge 304 which increases the ventilation over the transceiver248 that also generates a significant amount of heat.

FIG. 35 shows the card 208 mounted in the chassis 100 in relation to thesecond horizontal surface 142 and its ventilation structures. The guide214 of the card 208 is positioned within a knockout of the first row 144of the first ridge 183 as the card 208 is being inserted. In thisembodiment, once the card 208 is fully inserted, the guide 214 restspartially within a knockout of the second row 147 of the second ridge185. The first hole 218 of the guide 214 comes to rest over the secondrow of openings 314 of the second horizontal surface 142. The secondhole 220 of the guide 220 comes to rest over the third row 316 andfourth rows 320 of openings. The third hole 222 comes to rest over thesecond row of knockouts 147 in the second ridge 187. Thus, air is ableto pass through the openings and knockouts of the second horizontalsurface and pass through the guide 214 to absorb heat from thecomponents of the card 208.

In the embodiment shown, the capacitor 236 lies over the first row ofopenings 312. The DC-DC converter 238 lies over the first row 312 andsecond row 314 of openings and over the first guide opening 218. Therelay 244 and programmable logic device 246 lie over the third row 316and fourth row 320 of openings and over the second guide opening 220.Amplifiers 252, 254 and 256, 258 included in this embodiment on the card208 lie over the knockouts 147 and the third guide opening 222.

FIGS. 36A and 36B show a side view of an embodiment of the repeatercircuit board 234 of a card 208 suitable for installation in the chassis100. As discussed with reference to FIGS. 34 and 35, the repeatercircuit board 234 has several components positioned on the board 234 inrelation to the horizontal surface area 103, the ridges 300, 304 and therows of openings 186, 190, 192, 312, 314, 316, and 320 of the horizontalsurfaces 102, 142 of the chassis 100. The repeater circuit board 234includes a power supply capacitor 236, a DC-DC converter 238, and atransceiver 248 previously discussed. The board 234 has the LEDs 228,230, and 232 that provide the external visual indications of therepeater circuit's operation. Other components of the board 234 includebut are not limited to relays 240, 242, and 244, a programmable logicdevice (PLD) 246, an oscillator 250, isolation transformers 260, 262,and 264, 266, and first channel and second channel amplifiers 252, 254and 256, 258.

The embodiment shown in FIGS. 36A and 36B may be employed as a bridgingrepeater circuit that receives a low-level monitor signal throughconnector 225 and recreates the signal in a higher level suitable fornetwork transmission and sends it out through connector 225. Thebridging repeater circuit board 234 of FIGS. 36A and 36B may be usedwhere a digital signal cross-connect (DSX) of the network becomes faultyand must be replaced without interrupting signal transfer. The bridgingrepeater circuit bypasses the faulty DSX without interrupting signaltransfer by receiving monitor signals from healthy DSXs and providinghigh-level signals to the healthy DSXs until the healthy DSXs arepermanently connected together to bypass the faulty DSX.

The capacitor 236 of the embodiment shown is positioned such that theuncovered horizontal surface area 103 of the first horizontal surface102 is directly above it because the capacitor 236 does not need theextra ventilation provided by the larger openings 186, 190, 192 locatedbetween the ridges 300, 304 that are covered by the mesh cover 104. TheDC-DC converter 238 of this embodiment may be a model that is highlyflame resistant to enhance the flame containment of the chassis 100. Anepoxy encased DC-DC converter 238 such as the Ericsson PFK 4611SI issuitable in this embodiment. A monitor jack, which might ordinarily beplaced between the LEDs 230 and 232, is also absent in this embodimentto reduce the material on the board 234 that is susceptible to burning.

FIGS. 37A-E shows the alarm circuitry 272 of the repeater circuit board234. The alarm circuitry 272 controls the LEDs 228, 230, and 232. Duringnormal operation, the LEDs 228, 230, and 232 are one color, such asgreen, to indicate normal operation. The power LED 228 turns red if thelogic power plane 270 loses voltage from the output of the DC-DCconverter 238. This occurs due to relay 242 changing state in responseto the loss of logic power thereby causing voltage received directlyfrom the backplane connector 225 to activate the red diode of LED 228instead of the green diode.

The channel A LED 230 and channel B LED 232 are electrically connectedto the PLD 246 and to a logic ground plane 268. The PLD 246 receivespower from the logic power plane 270 and receives control signals fromthe transceiver 248. When a channel is operating normally, the PLD 246causes the green diode of the LED to illuminate.

If the transceiver 248 detects that channel A has no signal, then LOS0line passing from the transceiver 248 to the PLD 246 is triggeredcausing the PLD 246 to light the red diode along with the green diode ofLED 230 to create a yellow illumination. If the transceiver 248 detectsthat channel B has no signal, then LOS1 line passing from thetransceiver 248 to the PLD 246 is triggered causing the PLD 246 to lightthe red diode along with the green diode of LED 232 to create a yellowillumination. If either channel has a loss of signal, then a minor alarmsignal is generated and provided through the backplane connector 225 byrelay 244 changing state due to a control signal from the PLD 246. Theminor alarm line is electrically linked to a chassis ground plane 280.

If the transceiver 248 detects that it has failed, then the DFM linepassing from the transceiver 248 to the PLD 246 is triggered causing thePLD 246 to light the red diode and turn off the green diode of LEDs 230and 232 to create a red illumination. A major alarm signal is alsogenerated and provided through the backplane connector 225 by relay 240changing state due to a control signal from the PLD 246. The major alarmline is electrically linked to the chassis ground plane 280 as well withcoupling capacitors.

The PLD 246 and relays 240, 242, and 244 may be selected so as tominimize power consumption and reduce the amount of heat being generatedby each circuit board 234 in the chassis 100. The Atmel model ATF16V8BQLPLD draws only 100 milliwatts when active and is a suitable PLD forcontrolling the relays 240 and 244 and LEDs 230 and 232. The NAIS TX-Srelay draws only 50 milliwatts when active and is a suitable relay forcontrolling the LED 228 and the major and minor alarm signals.

FIGS. 38A-G show an embodiment of the transceiver circuitry located onthe board 234. The transceiver 248, such as the Level One model LXT332,is electrically connected to the logic power plane 270 and the logicground plane 268. The transceiver 248 is also electrically linked to achannel A power plane 274, a channel A ground plane 278, a channel Bpower plane 276, and a channel B ground plane 282. Each channel of thisembodiment has its own power and ground plane to avoid cross-talk and toavoid electrical noise from the power supply circuit of FIGS. 39A-G andchassis 100. The transceiver 248 is electrically linked to theoscillator 250 that is electrically connected to the logic power plane270 and logic ground plane 268. The oscillator 250 provides a referencefrequency signal to the transceiver 248.

The transceiver 248 receives its input signals for each channel from theinput amplifiers 252, 254 and 256, 258. The input amplifiers 252, 254and 256, 258 receive input signals from the backplane connector 225through the isolation transformers. Channel A input signal passesthrough isolation transformer 264 to the input amplifiers 256, 258, andchannel A output signal passes through isolation transformer 266.Channel B input signal passes through isolation transformer 260 to theinput amplifiers 252, 254, and channel B output signal passes throughisolation transformer 262. As shown in FIGS. 36A and 36B, the inputisolation transformer 264 and output isolation transformer 266 ofchannel A are contained in one unit. Similarly, the input isolationtransformer 260 and output isolation transformer 262 of channel B arecontained in another unit. Likewise, input amplifiers 252 and 254 ofchannel B are housed in one integrated circuit chip, and inputamplifiers 256 and 258 of channel A are housed in another integratedcircuit chip.

The input amplifiers 252, 254 for the tip and ring connections,respectively, of channel B are electrically connected to the channel Bpower plane 276 and also to the channel B ground plane 282 Likewise, theinput amplifiers 256, 258 for the tip and ring connections,respectively, of channel A are electrically connected to the channel Apower plane 274 and also to the channel A ground plane 278. Providingpower to the amplifiers of differing channels from different power andground planes reduces cross-talk and other electromagnetic interference.The input amplifiers 252, 254 and 256, 258 increase the amplitude of themonitor signal received by the bridging repeater circuit board 234 ofFIGS. 36A and 36B to a level within the sensitivity range of thetransceiver 248. The transceiver 248 is then able to recreate the signalhaving the higher level suitable for network transmission.

In the bridging repeater circuit embodiment of FIGS. 38A-G, the linebuild-out function of the transceiver 248 is fixed at a specific signallevel and shape because a consistent cable length is generally used whenconnecting the bridging repeater circuit between the healthy DSXs. Thus,line build-out variability is not needed. Resistors 284 are arranged toprovide a fixed connection between certain line build-out pins of thetransceiver 248 to the logic power plane 270 while providing a fixedconnection between other line-build out pins of the transceiver 248 tothe logic ground plane 268.

FIGS. 39A and 39B show the power supply circuitry. The backplaneconnector 225 receives −48V DC power and provides it through the board234 to the DC-DC converter 238. The −48V line and the −48 V return lineare linked by the capacitor 236 to eliminate ripple. These lines arealso coupled to the chassis ground plane 280. The DC-DC converter 238outputs a voltage that is electrically connected to the logic powerplane 270, the channel A power plane 274, and the channel B power plane276. The DC-DC converter 238 has a return that is electrically connectedto the logic ground plane 268, the channel A ground plane 278, and thechannel B ground plane 282. Ferrite beads are used to isolate each powerplane connected to the DC-DC converter 238 and each power plane is ACcoupled to each ground plane.

FIG. 40 shows a ground layer of the circuit board 234. The ground layerincludes the chassis ground plane 280 that extends around the periphery286 of the circuit board 234 and is electrically connected to thechassis ground provided through the chassis ground connector 138 of thechassis 100. The chassis ground plane 280 surrounds the logic groundplane 268, the channel A ground plane 278, and the channel B groundplane 282. The chassis ground plane 280, logic ground plane 268, channelA ground plane 278, and channel B ground plane 282 are copper sheetsthat are isolated from each other within the single ground layer of theprinted circuit board 234.

FIG. 41 shows a power layer of the circuit board 234 that is adjacent tothe ground layer and separated from it by a dielectric layer. The powerlayer includes the logic power plane 270, the channel A power plane 274,and the channel B power plane 276. The logic power plane 270substantially overlaps with the logic ground plane 268 of the groundlayer. The channel A power plane 274 substantially overlaps with thechannel A ground plane 278. Likewise, the channel B power plane 276substantially overlaps with the channel B ground plane 282. Thisarrangement minimizes electrical noise and cross-talk.

FIGS. 42A and 42B show a component layer of the circuit board 234. Theelectrical components previously discussed are typically mounted to thecomponent layer. The transceiver 248 is mounted in transceiver area 294.The isolation transformers 260, 262, and 264, 266 are mounted intransformer areas 296 and 298. It is generally desirable to minimize thedistance between the isolation transformer areas 296, 298 and thetransceiver area 294. A distance of one and one-third inches or less issuitable.

Also located on the component layer are chassis ground pads 290 and 292.These chassis ground pads 290 and 292 are electrically connected to thechassis ground plane 280. The metal faceplate 210 of the circuit card208 mounts to holes within the chassis ground pads 290 and 292 andmetal-to-metal contact is established between the chassis ground pads290, 292 and the faceplate 210. This metal-to-metal contact maintainsthe faceplate 210 at chassis ground.

FIGS. 51A and 51B show an alternative circuit board layout wherebyadditional surge protection is provided. The embodiment shown in FIGS.51A and 51B contains input amplifiers 252, 254 and 256, 258 but lacksline build-out switches. This embodiment has Schottky diode banks 360and 362 positioned between the isolation transformers 260, 262 and 264,266 and the transceiver 248. Each diode bank of this embodiment includesfour Schottky diodes. Additionally, this embodiment has a transientvoltage suppressor 364 positioned between the DC-DC converter 238 andthe bottom of the circuit board 234 which is close to the surface 142when installed in the chassis 100.

FIGS. 52A and 52B show the transceiver and the configuration of theSchottky diodes from each bank 360 and 362. This configuration ofSchottky diodes can be used with the transceiver configuration shown inFIGS. 38A-G. One Schottky diode of the bank 360 is tied between thechannel A power plane 274′ and the channel A tip output. AnotherSchottky diode of the bank 360 is tied between the channel A power plane274′ and the channel A ring output. Another Schottky diode of the bank360 is tied between the channel A tip output and the channel A groundplane 278′. The last Schottky diode of the bank 360 is tied between thechannel A ring output and the channel A ground plane 278′.

Channel B output is configured the same way with one Schottky diode ofthe bank 362 being tied between the channel B power plane 276′ and thechannel B tip output. Another Schottky diode of the bank 362 is tiedbetween the channel B power plane 276′ and the channel B ring output.Another Schottky diode of the bank 362 is tied between the channel B tipoutput and the channel B ground plane 282′. The last Schottky diode ofthe bank 362 is tied between the channel B ring output and the channel Bground plane 282′.

FIGS. 53A and 53B illustrate the power supply circuit that includesadditional surge protection. The DC-DC converter 238 of the circuit hasan output line and a return line that ultimately provide the channel Apower and ground, channel B power and ground, and the logic power andground. A transient suppressor 364 is tied between the output line andthe return line of the DC-DC converter 238.

FIG. 54 shows the ground layer of the circuit board 234 utilizing theadditional surge protection. In this embodiment, the chassis groundplane 280′ surrounds the periphery 286 of the ground layer and iselectrically connected to the chassis ground provided through thechassis ground connector 138 of the chassis 100. The chassis groundplane 280′ surrounds the channel A ground plane 278′, logic ground plane268′, and the channel B ground plane 282′. As with the previousembodiment, chassis ground plane 280′, logic ground plane 268′, channelA ground plane 278′, and channel B ground plane 282′ are copper sheetsthat are isolated from each other within the single ground layer of theprinted circuit board 234.

In this embodiment, the logic ground plane 268′ is positioned such thatit is partially between the channel A ground plane 278′ and the channelB ground plane 282′. The diode bank 360 is located on the componentlayer and in the area 368 positioned over the channel A ground plane278′. Similarly, the diode bank 362 is located in the area 366positioned over the channel B ground plane 282′.

FIG. 55 shows a power layer of the circuit board 234 that is adjacent tothe ground layer shown in FIG. 54 and separated from it by a dielectriclayer. The power layer includes the logic power plane 270′, the channelA power plane 274′, and the channel B power plane 276′. The logic powerplane 270′ substantially overlaps with the logic ground plane 268′ ofthe ground layer embodiment shown in FIG. 54. The channel A power plane274′ substantially overlaps with the channel A ground plane 278′ of theground layer embodiment shown in FIG. 54. Likewise, the channel B powerplane 276′ substantially overlaps with the channel B ground plane 282′of the ground layer embodiment shown in FIG. 54. As can be seen, thebank 360 of diodes is located on the component layer in the area 368positioned over the channel A power plane 274′. The bank 362 of diodesis positioned over the channel B power plane 276′.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that various other changes in the form anddetails may be made therein without departing from the spirit and scopeof the invention.

1. A chassis for holding telecommunications cards, comprising: a housinghaving first and second horizontal surfaces and first and secondvertical sidewalls, the first vertical sidewall having a plurality ofholes; and a first bracket mounted to the housing, the first brackethaving a first side and a second side perpendicular to the first side,wherein the first side of the first bracket has a first horizontaldimension and a first and second set of holes and wherein the secondside of the first bracket has a second horizontal dimension differentthan the first horizontal dimension and has a first and second set ofholes, wherein when the first set of holes of the first side of thefirst bracket align with at least a portion of the plurality of holes ofthe first sidewall, the second set of holes of the first side of thefirst bracket are blocked by the first vertical sidewall and when thefirst set of holes of the second side of the first bracket align with atleast a portion of the plurality of holes of the first verticalsidewall, the second set of holes of the second side of the firstbracket are blocked by the first vertical sidewall.
 2. The chassis ofclaim 1, wherein the second vertical sidewall has a plurality of holes,the chassis further comprising: a second bracket having a first side anda second side perpendicular to the first side of the second bracket, thefirst side of the second bracket having a first horizontal dimension anda first and second set of holes and the second side of the secondbracket having a second horizontal dimension different than the firsthorizontal dimension and a first and second set of holes; wherein whenthe first set of holes of the first side of the second bracket alignwith at least a portion of the plurality of holes of the second verticalsidewall, the second set of holes of the first side of the secondbracket are blocked by the second vertical sidewall and when the firstset of holes of the second side of the second bracket align with atleast a portion of the plurality of holes of the second verticalsidewall, the second set of holes of the second side of the secondbracket are blocked by the second vertical sidewall.
 3. The chassis ofclaim 2, wherein the number of holes of the second set of holes of thefirst side of the first and second bracket is three and the firstspacing distance is 25 millimeters, and wherein the second set of holesof the second side of the first and second brackets is four and thesecond spacing distance is 0.5 inches.
 4. The chassis of claim 1,wherein the first horizontal surface has a first ridge and the secondhorizontal surface has a second ridge, the first ridge and the secondridge being substantially perpendicular to a longitudinal axis of thefirst and second vertical sidewalls.
 5. The chassis of claim 4, furthercomprising a first horizontal cover overlaying the first horizontalsurface and a second horizontal cover underlaying the second horizontalsurface.
 6. A chassis for holding telecommunications cards, comprising:first and second horizontal surfaces and first and second verticalsidewalls separating the first and second horizontal surfaces, whereinthe first vertical sidewall has a plurality of at least three holes; anda first bracket having a first side and having a second sidesubstantially perpendicular to the first side, the first side having aset of at least two holes and the second side having a set of at leasttwo holes, wherein the set of at least two holes of the first side alignwith a first set of at least two but fewer than all of the plurality ofholes of the first vertical sidewall when the first side abuts the firstvertical sidewall and wherein the set of at least two holes of thesecond side align with a second set of at least two but fewer than allof the plurality of holes of the first vertical sidewall when the secondside abuts the first vertical sidewall, the first set comprising atleast one hole not included in the second set.
 7. The chassis of claim6, wherein the second vertical sidewall has a plurality of at leastthree holes, the chassis further comprising: a second bracket having afirst side and having a second side substantially perpendicular to thefirst side, the first side of the second bracket having a set of atleast two holes and the second side having a set of at least two holes,wherein the set of at least two holes of the first side of the secondbracket align with a first set of at least two but fewer than all of theplurality of holes of the second vertical sidewall when the first sideabuts the second vertical sidewall and wherein the set of at least twoholes of the second side of the second bracket align with a second setof at least two but fewer than all of the plurality of holes of thesecond vertical sidewall when the second side abuts the second verticalsidewall, the first set of holes of the second vertical sidewallcomprising at least one hole not included in the second set of holes ofthe second vertical sidewall.
 8. The chassis of claim 6, wherein thefirst side of the first bracket includes a second set of at least twoholes, and when the set of at least two holes of the first side of thefirst bracket align with the first set of at least two but fewer thanall of the plurality of holes of the first vertical sidewall, the secondset of at least two holes of the first side of the first bracket areblocked by the first vertical sidewall.
 9. The chassis of claim 6,wherein the first horizontal surface has a first ridge and the secondhorizontal surface has a second ridge, the first ridge and the secondridge being substantially perpendicular to a longitudinal axis of thefirst and second vertical sidewalls.
 10. The chassis of claim 9, furthercomprising a first horizontal cover overlaying the first horizontalsurface and a second horizontal cover underlaying the second horizontalsurface.
 11. A method of installing brackets on a chassis, comprising:providing a housing having first and second horizontal surfaces andfirst and second vertical sidewalls, the first vertical sidewall havinga plurality of holes; providing a first bracket having a first side anda second side perpendicular to the first side, wherein the first side ofthe first bracket has a first horizontal dimension and a first andsecond set of holes and wherein the second side of the first bracket hasa second horizontal dimension different than the first horizontaldimension and has a first and second set of holes; when installing thefirst bracket such that the first side abuts the first verticalsidewall, aligning the first set of holes of the first side of the firstbracket with at least a portion of the plurality of holes of the firstsidewall and blocking the second set of holes of the first side of thefirst bracket by the first vertical sidewall; and when installing thefirst bracket such that the second side abuts the first verticalsidewall, aligning the first set of holes of the second side of thefirst bracket with at least a portion of the plurality of holes of thefirst vertical sidewall and blocking the second set of holes of thesecond side of the first bracket by the first vertical sidewall.
 12. Themethod of claim 11, further comprising: providing a second brackethaving a first side and a second side perpendicular to the first side,wherein the first side of the second bracket has a first horizontaldimension and a first and second set of holes and wherein the secondside of the second bracket has a second horizontal dimension differentthan the first horizontal dimension and a first and second set of holes;when installing the second bracket such that the first side abuts thesecond vertical sidewall, aligning the first set of holes of the firstside of the second bracket with at least a portion of the plurality ofholes of the second sidewall and blocking the second set of holes of thefirst side of the second bracket by the second vertical sidewall; andwhen installing the second bracket such that the second side abuts thesecond vertical sidewall, aligning the first set of holes of the secondside of the second bracket with at least a portion of the plurality ofholes of the second vertical sidewall and blocking the second set ofholes of the second side of the second bracket by the second verticalsidewall.
 13. A method of installing a bracket on a chassis, comprising:providing a housing having first and second horizontal surfaces andfirst and second vertical sidewalls separating the first and secondhorizontal surfaces, wherein the first vertical sidewall has a pluralityof at least three holes; providing a first bracket having a first sideand having a second side substantially perpendicular to the first side,the first side having a set of at least two holes and the second sidehaving a set of at least two holes; when installing the bracket suchthat the first side abuts the first vertical sidewall, aligning the setof at least two holes of the first side with a first set of at least twobut fewer than all of the plurality of holes of the first verticalsidewall; when installing the bracket such that the second side abutsthe first vertical sidewall, aligning the set of at least two holes ofthe second side with a second set of at least two but fewer than all ofthe plurality of holes of the first vertical sidewall, wherein the firstset comprises at least one hole not included in the second set.
 14. Themethod of claim 13, comprising: providing the second vertical sidewallwith a plurality of at least three holes; providing a second brackethaving a first side and having a second side substantially perpendicularto the first side, the first side having a set of at least two holes andthe second side having a set of at least two holes; when installing thesecond bracket such that the first side of the second bracket abuts thesecond vertical sidewall, aligning the set of at least two holes of thefirst side of the second bracket with a first set of at least two butfewer than all of the plurality of holes of the second verticalsidewall; and when installing the second bracket such that the secondside abuts the second vertical sidewall, aligning the set of at leasttwo holes of the second side of the second bracket with a second set ofat least two but fewer than all of the plurality of holes of the secondvertical sidewall, wherein the first set of holes of the second verticalsidewall comprise at least one hole not included in the second set ofholes of the second vertical sidewall.